ANTANANARIVO, Nov 20 (Reuters) - Madagascar’s army stormed a barracks housing dissident officers on Saturday and ended a four-day mutiny by the group who wanted to overthrow President Andry Rajoelina.

The rebel officers proclaimed their plans from the barracks on Wednesday as the country was voting in a referendum on a new constitution. They called on other soldiers to join their cause, but the call went unanswered.

Witnesses said there were sustained bursts of gunfire and sporadic shots for more than 20 minutes following the assault on Saturday by about 100 men. Soon after the shooting stopped, a convoy of more than a dozen vehicles left the barracks, located on the outskirts of the capital Antananarivo.

“(The rebel officers) were ready to give themselves up but lower-ranking soldiers opened fire,” Colonel Julien Ravelomihary, who was at the camp, told Reuters.

Another soldier who took part in the assault said the officers eventually surrendered.

An official at the military police, who declined to be named said 16 dissidents had been detained. Six had been taken to the Tsiafahy Prison while 10 others were being held at a military police barracks for further questioning, he said.

The charges against the dissidents included rebellion and threatening the security of the strength.

The storming came a day after army chiefs held talks with the officers to try to resolve the standoff without resorting to force, despite earlier government vows to crush any rebellion.

Political analysts had said the longer the stand-off endured the more damaging it would be to Rajoelina and his administration, as it was starting to look as though the army was reluctant to carry out orders.

DISQUIET

The unrest in Madagascar, the world’s fourth largest island and biggest producer of vanilla, underscores the depth of internal rifts plaguing the army since Rajoelina drove predecessor Marc Ravalomanana into exile last year.

Rajoelina had called Wednesday’s referendum to replace the constitution cast aside when he took power. Among changes, it would lower the minimum age for the president from 40 to 35; Rajoelina is 36. The opposition had called for a boycott.

Provisional results on Thursday from around 1,000 of the more than 18,000 polling stations showed the “Yes” camp well ahead. Turnout was just under 50 percent.

Rajoelina, the former mayor of Antananarivo, rode to power on the back of protests against Ravalomanana’s increasingly autocratic rule. But Rajoelina’s failure to deliver on populist pledges has cut into his public support.

The backing of army chief of staff General Andre Ndriarijoana and other officers was the turning point in Rajoelina’s struggle to oust Ravalomanana last year. Some of those officers who backed Rajoelina’s power grab were the ones calling for him to quit this week.

Rajoelina has so far failed to win acceptance of the international community. The United States froze development aid and the African Union slapped sanctions on him and 100 of his supporters.

Internationally-brokered power-sharing deals between Rajoelina and three opposition parties headed by former presidents floundered amid bickering over top government posts.

A summit of the regional Southern African Development Community (SADC) on Saturday said it did not support Madagascar’s referendum because the political roadmap was organised without agreement of the main opposition.

Executive Secretary Tomaz Salamao told journalists SADC would be sending a facilitator to Antananarivo next week to assess the situation on the ground and what could be done to resolve the situation.

Recurring political ructions over the past year have battered the economy in Madagascar, where foreign firms are developing oil, nickel, cobalt and uranium deposits. (Writing by David Clarke; Editing by Peter Graff) (For more Reuters Africa coverage and to have your say on the top issues, visit: af.reuters.com/)